Chemical Technology August 2016

gainst a background of growing demands from

the water and wastewater treatment industries

for submersible motor pumps that resist clogging,

deliver reliability and contribute to improving energy ef-

ficiency, KSB AG has developed a new centrifugal pump,

the Amarex-KRT F-Max (Figure 1) that addresses these

issues. Improved hydraulic system and motor performance

are delivered through the design of a new vortex impel-

ler and a motor that offers efficiencies currently calcu-

lated according to the same IEC 60034-2 measurement

method as that used for motors of dry-installed pumps.

In order to attain a pump’s optimum operating point,

it is essential to select the correct impeller and size of

impeller for the application. Whilst free-flow or ‘open’

impellers enable suspended solids in wastewater to pass

more easily through the pump than closed single channel

or multi-channel impellers, they do not compare favourably

when it comes to performance. It is for these reasons that

KSB has focused on designing an open impeller that can

achieve and even exceed the efficiency levels associated

with single-channel impellers. To improve overall efficiency,

KSB has looked to optimise the motors’ efficiency in an-

ticipation of future standards and market requirements is

in compliance with IE3.This has enabled KSB to markedly

reduce energy consumption.

Impeller development

The concept behind the design of the new pump is the

elimination clogging, a problem that causes inefficient

flows and possibly subsequent pump failure through the

presence of solids in wastewater. According to KSB the first

stage in finding a solution to clogging was to differentiate

between rigid and non-rigid solids. Michael Lebkuecher,

who headed the product management solid burden pumps,

comments: “Rigid solids need to have sufficient space in

the pump chamber for them to pass through the pump.

When it comes to non-rigid solids we have to ensure that

the presence of wet tissues and similar fibrous materials

do not form a mass. These problems were resolved, but

then the next challenge was to address overall efficiency.”

New impeller combines reliability

and efficiency

by Bryan Orchard

Growing demands from the water and wastewater treatment industries for

submersible motor pumps that resist clogging, deliver reliability and contribute to

improving energy efficiency, have led to KSB AG’s new centrifugal pump.

Chemical Technology • August 2016

Figure 1: The new Amarex KRT F-Max.

PUMPS AND VALVES